5. Process Improvement
5.2. Introduction
5.2.4. What are the elements of a simple experiment?

5.2.4.2.

Main effects

There are 3 basic models used for most DOE's
 
 
 
 

The Main Effects model is the simplest model (and assumes no interactions are present)

There are three main model types, all simple polynomials.

1. A Main Effects Model
2. An Interaction Model
3. A Response Surface Model

This page covers the main effects model. The next page describes the other models.

The Main Effects model

                         Y = a + bX₁ + cX₂

where X₁, X₂ are inputs (factors), Y is an output,  a, b, and c are the model�s coefficients which are all assumed constant. Here we have just two inputs, but we could, of course, have many more inputs.

Our experimental design is aimed at collecting data to estimate a, b, and c, and to tell us which if any of X₁ and X₂ are important. A conventional way of writing the model (used in many software packages) is:

                         Y = b₀ +  b₁ X₁ + b₂ X₂.